Pest
Plum Leafroller
How to identify if your tree has it.
The plum leafroller is a worm that rolls up the leaves like a cigar. Observe your tree for rolled leaves and feeding damage in fruit clusters. You may find the small green worm if you unfurl the leaf. You may also see some minor webbing and black worm excrement.
What kind of damage does it cause?
The larval stage feeds on fruit and leaves. Prebloom feeding can result in fruit abortion or deeply scarred fruit.
What to do if your tree has it.
The preferred method of eradication when they are present is hand picking the affected leaves from your tee. However, if the entire tree is infested with live worms, there is a commercial biological-based spray (Bacillus thuringgiensis, or Bt) that is safe for humans and dogs but detrimental to the guts of the worm. It requires multiple applications to be effective.